Skeleton plugins might be uneccesarily duplicated

[mdoube]

Describe the bug Skeletonize3D and AnalyzeSkeleton are called from BoneJ via Modern wrappers. Recent work (#257 #256) on BoneJ highlighted the potential redundancy and duplicated effort involved in maintaining Modern wrappers for otherwise unchanged third party plugins, to which we are readily able to contribute.

A proposed solution is to remove the wrappers, and make improvements upstream instead.